Saline tri-sodium phosphate and process for its manufacture



' caustic soda necessary for Passes Get, 1928.

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f cnaa'ms is; soon: AND Amigos 13. GERBER, or: amirsroiw memn, Ann PAUL.

' LOGUE, or LOG-UE, m ssoo u.

mm rm-SODIUM rnosrimrn am) Paocsss roams morn muss.

Hem-swing, sealin r application Serial No. 720,919, meamyiai eze. This application am me 25,

1 28.- Serial No. zaaas'a, I

p This invention relates to a process for the manufacture of compounds of alkali-metal phosphate ,and particularly to the manufac tureof a sodium chloride 'tri-sodium phos-,

6 phate compound such as referred to in our co-pending application, Serial No. 726,920.

, The object of this invention is to. produce-- a compound requiring in its manufacture less caustic than is now used in the manufacture of commercial tri-sodlum'phosphate. It follows that the material provided by our present process will contain less freecaustic and,

be less injurious to handling it. According to the present. practice, trlsodium phosphate is generally manufactured by theneutralization of sodium carbonate, which is commercially calledsoda ash, with phosphoric acid, whereby di-sodium phosfabrics andto individuals phate is produced.,- After theproduction of di-sodium' phosphate, it is causticized by the addition of caustic soda, thus converting-the *di-sodium phosphate into tri-sodium phosphate. The resultant tri sodium phosphate solution. is then cooled in a suitable manner and solid tri-sodium phosphate separated out as a crystalline material. Based on the following chemicalequations:

Na,Po,-.12H,o+H,0 the theoretical quantities of materials neces- .sary for the -production. of tri-sodium phosphate are as follows:

phosphate. a a '27.8# Na CO," per 100# tri-sodium phosphate.1'- I I .41; y I 1o.5#' NaOH per 1004; tri-so'di mjphos' p ate. a -1 v Actual practice from sevemlyears opera tion shows that in so far as "theca'ustic is concerned this quantity is insuficient, and as tion it appearsthat the material whichis come jmercially called .tri-sodium phosphate does but :contains in addition 'N'aOH and 726,918,

. tity of caustic required- *"tures'the reduced caustic considerable advantage so ar as the cost of production. wasconcerned, because it is pos-'v .sible to make this new compound with' apj ya result of. this increased causticconsump not' conform to :the formula .Na ,P0,-.1i"2H,OT

1#-than the theoretical 10. 5# NaOI-I as given aboveJJEXtensiVe experiments; were reduce-the quantity .of caustic necessary in tri-sodium phosphatema'nufacture as that element is both expensive and objectionab1e-. During this investigation it was discovered that it was possible to produce tri-sodium phosphate by the use of less caustic soda, and

the resulting compound having a ratio of 0.50 when titrated with a standard acid, using phenolphthalcin and 4 methyl orange as indixcators. We have found that a different compound canbe produced from this neutral tri-- sodlum or di-sodium' phosphate solution by the addition of sodium chloride, the addition of which to the tri-sodium or- .di-sodium phosphate solution improved'the crystallization of the tri-sodium phosphate compound. This invention relates to the process by which pound-is produced in connection with the After considerab e experimental work in the effort to increa e the size of crystals. of the -tri sodium' phosphate produced as -described, in aplplications, Serial Nos. '726 917 edJuly 19, 1924, by A.v B. er-

abovementioned sq'ldiumsalt."

-tr i-sodium phosphate approaches nearer conducted to determine if it were possible to 'a sodium chloride tri-sodium phosphate comher and. O. F. Booth, it was found that by.

the addition of common salt (N a'Cl), it was possible to produce materials having all the desirable characteristics of the alkaline or commercial tri-s'odium phosphateas found on the market at present also,

the latter was unnecessary.- It was "also found that the new material'thus produced did not have thesame harshcaust cdr'ying the large. quan-. or the production of action on the skin as the alkaline or com- 4 market at present. In addition to these feauirement was of;

' mercia'l tri-sodium phosphate as found on the.

proximately the theoretical requirement 20f- 'lein end point to sodium p'h .acid used,

a slight acid end point with the methyl 7 --will therefore be seen that of this new compound by our process, ofiers, distinct economic advantages over the manu- I Theprocess andequipmentchloride. For instance, the compound is be lieved to have a formula a sgiv ro iaii oyiiao fact that the half normal hydrochloric acid solution usingphenolphthalein and methyl orange as indicators.

When the end point for the phenolphthalein is reached, a reading is made of-the and the titration is continued to orange. The reading of. the titration of the phenolphthalein is then-divided by the sum of the readings, andfa ratio of 0.46 to 0.50 is the desired resultant for the optimum conditions to produce the best yield of sodium chloride tri-sodium phosphate crystals when the solution is cooled. The ratio. so determined is one means .of deriving a constant p as a measure of the caustic present in the solution or crystals. Where the 'term ratio is used herein it refers to-such method of determination of the relation of phenolphthamethyl orangeindicator end point in the solution ospha'te or crystals thereof. It the production facture of alkaline or commercial trifodium phosphate as produced at the present time, and in addition to this economic feature, a sodium chloride tri-sodium phosphate compound is produced which has distinct advantages for the consumer. ture is similar to that carried on and used in the manufacture of alkaline or commercialfltri-sodium phosphate as found on the market at present. "According to'our process, phosphoric acid is neutralized by add-.

ing sodium carbonate (Na Co to di-sodium phosphate and 4% sodium chloride-(Nam) is added-to the di-sodiumphosphate solution. After the sod'u'm chloride addition, the necessary caustic is addedto conform approximately to the chemical equation as follows: i

'chlori e-being required N m-man o +n 0.

The amount of sodiumichloride ,variesaccordin to the titration ratio, more sodium of sodium chloride triq.

of manufac the requirement as given in tri-sodium p with a high ratio.

After the sodium chleride tri-sodium phosphate solution is tested as described above, it is cooled in any suitable manner and the sodium chloride tri-sodium phosphate crystals separate out. They may be dried in a 7 centrifuge or any other suitable means 0 dewatering, and then steam or air dried to remove the surface moisture. "After. drying, the crystals are ready for shipment.

The following proportions are given-as 7 illustrative of the mixture required in mak ing the above described sodium chloride tri-. sodium phosphate compound by our process:-

4e# H.130, 25.2w 1,1 0. n

commercial soda ash (58% 11# caustic soda (16% Na O) 8# sodium chloride. The acid is neutralized by the soda ash and any impurities such as iron, and calcium phosphates which are precipitated, are removed from the solution, pref-' erably by filtration. The di-sodiumphosphate solution is boiled-prior to filtration in i order that the carbon dioxide (CO may be eliminated. After filtration salt a dcaustic soda are added andthe solution thoroughly mixed. The mixture is the'ntested accor ing to thepreviously outlined method and if sufiicient caustic has not'been added, an addition is made .until the titration gives thedesired figure; while if an excess; of caustic has-been added, di-sodium hosphate solution is added to reduce the gure to the de-v sired point. The same requirement can be used for'the subsequent coolin ,-crysta1lization, dewatering and drying of this product as forthe alkaline or commercial tri-sodium phosphate as found on the market at present.

When we refer to alkaline or commercial tri- 1'05 sodium phosphate, as found on the market at present, we mean to-include its compounds,

whatever thecomposition maybe. y

, Having thus described our invention,-what we claim as new and desire to secure by Letters Patent, is 1. The herein described process-for the manufacture of a sodium chloride tri sodium phosphate composition, which consists combining phosphoric acid, sodium' carbonul ate and caustic soda' with sodium chloride water. 9 i

'2. The herein described process for-the manufacture of a sodium chloride tri-sodiuin phosphate composition, which consists-m 12 combinin boncentrated phosphoric acid, so-

car onate, and caustic diumchloride and lution and se soda with sowater and cooling the so:

arating out the sodium" chloride sphatecomposition in crystal- 1:

line form.

The titration ratio varies from a proxi- 3.The herein described process for the m'ately 0.46 to 0.50, depending upon t e con manufacture of a sodium chloride tri-sodium centration of the solution, a high ratiof'be-o' phosphate coiriikpsition, which consists .in' ing used for higher concentrations. f phosphoric-acid, sodium carbon- 1 alumina, 85

' scribed.

ate, and caustic 'soda solution with sodium chloride andwater, and'separating out the I crystalline product.

1 4. Thejherein described process for the manufacture of a sodium chloride tri-sodium phosphate composition, which consists inrthe addition of sodium chloride and caustic soda to di-sodium scribed. I

5. The herein described process for phosphate, substantially as desolutions to (ii-sodium phosphate solution, substantially as described.

. 6. The herein described steps in the process for the' manu-facture of a sodium chloride trisodium phosphatemomposition, which consists in the neutralization of phosphoric acid with sodium carbonate, removing all solids thus formed, and adding sodium chloride and caustic'soda, substantially. as described.

' 7 .I The herein described steps in the process i for the manufacture ofa sodium chloride trisodium phosphate composition, which con- .sistsin neutralizing dilute phosphoric acid with sodium carbonate, removing all solids thus formed, concentrating the di-sodium phophate solution, and adding sodium chloride and caustic soda, substantially as de- 8. The herein described steps in the process for the manufacture of. a sodium chloride tri-sodium phosphate composition, which consists in neutralizing concentrated :phosphoric, acid with sodium carbonate, remov f ing all solids thus formed, concentrating the sou tion, adding sodium chloride and caustic soda, and coolingand crystallizing the sothe manufacture of a sodium chloride .tri-sodium' phosphate composition, which consists in the addition of sodium chloride and caustic soda dium chloride tri -sodium phosphate composition, substantially as described.

9. The herein described process for the manufacture of a sodium chloride tri-sodium phosphate composition, which consists in add- 4 mg sodium chloride and caustic soda to disodium phosphate solution, concentrating the solution, and cooling and crystallizing a sodium chloride tri-sodium phosphate composition therefrom, substantially as described.

10. The herein described composition of matter consisting of a compound of sodium phosphate and sodium chloride.

11. Therein described compositionof matter consisting of a compound of tri-sodium phosphate and sodium chloride.

12. The herein described composition of matter consisting of sodium phosphate and sodium chloride in a-crystalline. form.

13. The herein described composition of matter consisting of tri-sodium phosphate and sodium chloride in a crystalline form.

14. The Herein described sodium phosphate composition containing approximately 3% dium phosphate composition crystallized from a sodium phosphate solution containing approximately 4% sodium chloride.

In testimony whereof we aflix our signatures.

CHARLES F. BOOTH. ARTHUR B. GERBER. PAUL LOGUE. 

